This is my first model that I really like and feel I did a good job texturing to this point. Just looking for comments about the quality. The top geometry is flat I know. This took me ~3 hours.

Not bad, definitely better than anything I can make. It would be really great with the geometry finished, and some nice bumpmapping, but it is a great start.

We could make a better determination of that model if you were to render a wireframe version and one of your texture map, so we can see the UV mapping. Take a look at game art on CGTalk if you want to see examples.

Well, i assume your diffuse is still wip. But you need to dirty it up a bit in more targeted areas, and add some functional and non-functional details too. Add vehicle decals that are worn down a bit, add dirt around the base of the tank...etc.
However, for better crits we do you to see your wireframe and possibly your texture flats to see how things like your uv layout are. Though, it would help if you don't place your model on a detailed background, its good for beauty and presentation renders but kind of distracts in critiquing.

Not bad for 3 hours ;)

I would like to see lots more detail on the top section (such as a hatch so you can climb in/out). You could probably add a bit of variety to the sides too, such as maybe some more ventilation areas. I can't really comment on the back, because it's not visible in your render.

Another model. 2-3 hours.

your texture looks a little stretched on the second model at the front. Looks pretty good!

What program are you using to model your objects?

Looks like some sort of tank winnebago hybrid

I'm using blender for models, Gimp for textures.

Yea if you look up "MULE" is a military vehicle. I have one slight part of geometry not in, which kinda makes it look like an RV.

Yeah, the texture looks stretched on the second one. Other than that, the base texture looks good.

Since this is most likely for a game (or practise for one) I'd use the Burn and Dodge tools to simulate soft shadows and lighting, since most games don't use real-time self-shadows. Try darkening up the small area around the missiles, so they don't look like they're just "sticking out."

Overall, pretty good!